1. Field of the Invention
The present invention relates generally to positive displacement rotary machines and engines and, more particularly, to turbines.
Positive displacement rotary machines have been used for pumps and engines. Pumps have been implemented in a variety of forms, from linear reciprocating pumps, such as are found in household tire pumps and in most automobile engines, to axial flow and centrifugal pumps such as exist in modern day turbomachinery, and screw and worm pumps. Rotary Wankel engines are one example of positive displacement engines. Axial flow turbines have a wide range of applications for extracting energy from a fluid because of the ability to provide continuous near steady fluid flow. It is a goal of turbine designers to provide light-weight and compact devices. It is another goal to have as few parts as possible in the turbine to reduce the costs of manufacturing, installing, refurbishing, overhauling, and replacing the device.
2. Brief Description of the Invention
A continuous axial flow positive displacement worm turbine includes a relatively high pressure inlet axially spaced apart and upstream from a relatively low pressure outlet. A rotary assembly includes an inner body disposed within an outer body and extending from the inlet to the outlet. The inner and outer bodies have offset linear inner and outer axes about which they rotate or spin, and intermeshed inner and outer helical blades wound about the inner and outer axes respectively. At least one of the inner and outer bodies are rotatable about a respective one of the inner and outer axes. In a preferred embodiment of the worm turbine, the inner and outer bodies are both rotatable about the inner and outer axes respectively.
The inner helical blades extend radially outwardly from an annular inner hub of the inner body and the outer helical blades extend radially inwardly from an annular outer shell of the outer body. The inner hub and the outer shell are circumscribed about the inner and outer axes respectively. The number of the inner helical blades and the number of outer helical blades is each two or more and the number of outer helical blades is one more or one less than the number of inner helical blades. The inner helical blades extend radially outwardly from an inner hub of the inner body and the outer helical blades extend radially inwardly from an outer shell of the outer body. Both bodies are rotatable about their respective axes and rotate in the same direction.
The inner and outer bodies are rotatable about the inner and outer axes respectively in the same inner and outer rotational directions respectively and the inner and outer bodies are geared together in a fixed gear ratio. In one particular embodiment of the turbine, the helical blades have sufficient number of turns to trap fluid charges in the rotary assembly during the turbine's operation. In one particular embodiment of the turbine, the number of outer helical blades is one less than the number of the inner helical blades and the inner body is operable to orbit about the outer axis in an orbital direction and the orbital direction is same as the inner rotational direction.
In another particular embodiment of the turbine, the number of outer helical blades is one more than the number of the inner helical blades and the inner body is operable to orbit about the outer axis in an orbital direction opposite the inner rotational direction.
One embodiment of the turbine includes the outer body being orbitably fixed about the inner axis and the inner body being operable to orbit about the outer axis. Another embodiment of the turbine includes the inner and outer bodies being rotatable about the inner and outer axes respectively in same inner and outer rotational directions respectively and the inner and outer axes are fixed in space and thus neither body orbits the other.
In one embodiment of the turbine, a first ratio of the outer body twist slope of the outer helical blades to an inner body twist slope of the inner helical blades equals a second ratio of the inner number of the inner helical blades on the inner body to the outer number of the outer helical blades on the outer body.
The turbine may have first and second sections with first and second twist slopes of the inner and outer helical blades respectively with first twist slope being greater than the second twist slope.